Cloning and production of Xylanase B fromPaenibacillus barcinonensisinBacillus subtilishosts

Advances in the understanding of the production, modification and applications of xylanases in the food industry

Xylanases have broad applications in the food industry to decompose the complex carbohydrate xylan. This is applicable to enhance juice clarity, improve dough softness, or reduce beer turbidity. It can also be used to produce prebiotics and increase the nutritional value in foodstuff. However, the low yield and poor stability of most natural xylanases hinders their further applications. Therefore, it is imperative to explore higher-quality xylanases to address the potential challenges that appear in the food industry and to comprehensively improve the production, modification, and utilization of xylanases. Xylanases, due to their various sources, exhibit diverse characteristics that affect production and activity. Most fungi are suitable for solid-state fermentation to produce xylanases, but in liquid fermentation, microbial metabolism is more vigorous, resulting in higher yield. Fungi produce higher xylanase activity, but bacterial xylanases perform better than fungal ones under certain extreme conditions (high temperature, extreme pH). Gene and protein engineering technology helps to improve the production efficiency of xylanases and enhances their thermal stability and catalytic properties.

Research Progress on the Effect of Autolysis to Bacillus subtilis Fermentation Bioprocess

Bacillus subtilis is a gram-positive bacterium, a promising microorganism due to its strong extracellular protein secretion ability, non-toxic, and relatively mature industrial fermentation technology. However, cell autolysis during fermentation restricts the industrial application of B. subtilis. With the fast advancement of molecular biology and genetic engineering technology, various advanced procedures and gene editing tools have been used to successfully construct autolysis-resistant B. subtilis chassis cells to manufacture various biological products. This paper first analyses the causes of autolysis in B. subtilis from a mechanistic perspective and outlines various strategies to address autolysis in B. subtilis. Finally, potential strategies for solving the autolysis problem of B. subtilis are foreseen.

Recombinant expression of an alkali stable GH10 xylanase from Paenibacillus barcinonensis

Xylanase A from Paenibacillus barcinonensis, a new species isolated from a rice field, has been cloned and expressed in Escherichia coli. Purified recombinant xylanase showed high activity on xylans from hardwoods and cereals, and exhibited K(m) and V(max) of 2.93 mg/mL and 50.67 U/mg on birchwood xylan. Xylanase A was highly active at 60 degrees C in alkaline pH values up to 9.5 and remained stable for at least 3 h in alkaline conditions. The amino acid sequence deduced from xynA revealed that it is a single domain xylanase belonging to the GH10 family. Thin layer chromatography analysis showed that the enzyme released a mixture of hydrolysis products including substituted xylooligomers from cereal arabinoxylans, while xylose, xylobiose, and aldotetraouronic acid were the main products released from glucuronoxylan from birchwood. The enzyme released a complex mixture of xylooligomers for acetylated xylan from eucalyptus, revealing its potential to depolymerize this widely used resource in the pulp and paper industry.